Wednesday, January 2, 2019

Happy New Year! A Cone 9 - 10 dolomite matte glaze for you to try!

I think that Santa and his cat must have gone fishing this Christmas, and the postcard that he sent me is evidence of this! The great day came and went in rather a rush and left us a bit surprised that it had been there at all. Laura and I were fairly tired in the run up to Christmas, so we had a quiet day at home, just the two of us... well, 4 really when we include the cats!

I did try to get this card finished and sent away on Christmas Day, but it didn't quite happen, so here it is now as a Christmas/New Year thing.

At this time of year it is usual for people to drop in! We were delighted to meet up with Gwynneth and Vic (The Pirate) who I have read about for several years now on "Ook?!" Gwynneth's blog. Gwynneth is a very experienced and accomplished potter and does lovely linocuts as well, and Vic is a retired aircraft engineer. They are currently in New Zealand intending to compete in cycling events at the Masters Games and were able to travel far enough South this time to come and see us.

It is lovely to meet other bloggers "in the round" as it were, and we made sure that we remained comfortably three dimensional by having an evening out with them and feasting together on yummy wood fired pizzas at "Salt and Sugar" the Karitane General Store in the next village!

Gwynneth, Laura and Vic
 Vic is 20 years my senior, and was able to confirm what the weather was like in the village of Rye where I was born on the day of my birth! Vic was taking part in a cycling event near Rye in the UK on that Blessed Day, and attests to the fact that the weather was just as appalling as it is in my mother's account of things! ("It was a dark and stormy night, my son, and the Midwife could not get to you in time....., etc"). Vic has a photo of another competitor sheltering under a cape as the rain pours down. What fun!

Meeting such lovely people is a happy/sad thing as there is always so much to talk about, and never enough time, but we are really thankful for the hours we had and for the enduring warmth of friendship.

Christmas, and the week or so after it, is an odd tumble of days which quickly lose their comfortable labels of Monday, Tuesday, Wednesday and the like, and today, which my calendar informs me is a Tuesday, really feels like Saturday because it is New Year. In spite of the uncertainty, I have managed to get a glaze firing through the electric kiln and should have some new bowls to put out in our little gallery tomorrow, all going well!

Recently I was pleased to rediscover one of my gazes that I had developed in 2014, a dolomite matte glaze that was intended to be a useful substitute for an old faithful glaze that I had used before when I could still get Cornish Stone at a sensible price... and "proper" Cornish Stone, not the less interesting substitute that you get these days. Real Cornish Stone from Cornwall UK was a fascinating material. A complete high temperature glaze in itself, this natural material contained the glass former silica, the stabilizer alumina, and fluxes sodium, potassium and calcium, with the interesting addition of a trace of Fluorine (if you were lucky!). Quite a nice high temperature clear glaze could be made from it by adding just a little more flux, such as 8 - 12 percent calcium carbonate.

By studying the chemistry of the various natural materials we use for potting it is possible to make reasonable substitutes in some cases, but they are never really the same as the natural ones, that doesn't mean that they are necessarily inferior, just different, rather like family members that look much the same, but have unique personalities!

At the time that I made the glaze, I did not do a great deal with it other than use it on a few test pieces, and 2 liters sat for 4 years in a bottle, not coming to any harm as such, but looking rather neglected! At the time I probably found the glaze OK, but not hugely inspiring on the rather iron rich stoneware clay I was using. Now I am using a porcelain body I am really delighted with the result.

Here is my Dolomite Matte recipe. This is a cone 9 - 10 glaze and I have only tried it thus far in oxidation, but suspect it will perform OK in reduction too. Best on porcelain or white stoneware. Stores well!!

Soda Feldspar    25
China Clay          25
Silica                   20
Dolomite             15
Potash Feldspar  10
Whiting                 5
Talc                       3

Total = 103

I tried the glaze on some rice bowls that I had "thrown off the hump", and I improvised some fish with brush decoration in cobalt and red iron oxide. The little bowls really feel and look just right so I am very pleased.

Happy New Year to you all!


Anna said...

How great to have that connection with Gwyneth and her husband... I love meeting up with other pottery bloggers too... I do follow Ook so will watch to see what she says about her travels.
Love the fishes.
Happy New Year to you and Laura

Peter said...

Happy New Year Anna,
It certainly is fun to meet with bloggers in addition to the exchange of comments and messages, we have some lovely memories to treasure of such times.
We are actually having the occasional warm summer day here now where we get almost to 30 degrees outside. I am enjoying the relative coolness of our old building on those days, it really is nice in my studio then where we probably reach the low 20s. I suspect those are more like winter temperatures for you!!! :-)

charlie said...

hi Peter .Glad to see you are posting again and potting as well! Very nice brushwork on the fish.Love them.Kind regards Charlie Seakins in Auckland

Peter said...

Hi Charlie,
Lovely to hear from you all the way from sunny Auckland! Thank you so much for your encouragement. More bowls are drying on my drying shelves as I write. I am enjoying the brush decoration, something I haven't done much of for a long time, and it is really good fun improvising fish designs.

PP said...

Happy New Year Peter - nice to find a new post on the blog.

It's lovely when blog contacts turn into meetings with actual people. I used to write a blog about the house we restored in Sydney and made a couple of good friends from doing that.

The bowls are lovely and I thought I'd give the glaze a go (I've just made up a quantity of the de Boos flecky green). Could I ask whether the dolomite matte is translucent or opaque (a glazer could tell from the ingredients, but I'm not a glazer!) and whether you think colours could be added to it, either stains or the usual coppers etc?

Whilst browsing glazy the other day I saw several of your recipes there, all fully attributed to you. Nice to see them getting around.

Peter said...

Happy New Year PP,

It certainly is nice to meet actual people, the internet can make the world a more friendly place after all!!

Do give the dolomite matte a go. You will probably find the glaze almost opaque, but not completely so. It does not have opacifiers such as zircon, or tin oxide, but the nature of a matte glaze like this is to be composed of thousands of tiny crystals which effectively scatter the light and make it look "solid" rather than glassy and clear.

I have not experimented with adding colours to this glaze as yet, because I haven't used it a great deal, but it will probably respond in a similar way to other matte glazes that have magnesium and calcium. As it is a matte glaze it would be best to aim for pastel shades rather than strong colours.

These are all guesses, but.... Cobalt blue will probably give a slightly violet shade of blue. On its own chromium oxide would very likely give brown, but could be used in small amounts of about 0.5 percent to modify copper or cobalt. I suspect that 1 - 2 percent iron oxide may give more of a pale yellow-brown, and 1 - 2 percent copper carbonate a pale, but slightly dull, green.

Do try it and let me know how you get on! :-)

I do like what are doing, it is a most useful site, and... I must start to put some glazes up there myself. It is nice to see some of mine there already.

Best Wishes,


Linda Starr said...

happy new year to you and Laura, those are some sweet bowls and nice to see a blogging friend in person.

Anonymous said...

Hi Peter, I shall fire a test of your glaze in my cone 10 reduction fire in early February if all goes well, and will let you know how it turns out for me. I’ve followed Gwyneth’s blog over the years and great to see that she and the pirate made landfall in your part of the world. Lovely brushwork on your bowls! Cheers from Oregon, Owen

Peter said...

Happy New Year Linda,
Very nice to hear from you. Thank you for the encouragement you have been to me over the years, the blog has been a great way of "traveling" from one side of the world of the other even though it has mostly been through words and pictures!
Kind Thoughts to you and Gary,
Peter & Laura

Hi Owen,
Good to year from you. It would be wonderful help if you could do a test of the matte glaze in reduction, it will be very interesting to see how it turns out. I would expect a slight satin sheen in reduction, and it might give a grey celadon over an iron bearing clay. I have been glazing some more bowls with the same glaze this afternoon for a firing in the electric kiln. All going well, I will find the time to do the brush decoration tomorrow.
Happy New Year to you,

PP said...

Hi again Peter

Thank you for you reply. I'll give the new glaze a go, and experiment with a few colours and I will indeed let you know how I go.

I tried yesterday to post a photo here of some test mugs I made with your green/blue flecky, but had no luck. When I figure out how to do it, I'll have another bash. You said in a previous post that you only need a couple of good glazes, and I think this one will be one of mine (especially since I mostly make unglazed non-functional stuff). It has such a lot of movement and interest - the almost violet speckles running through it are lovely. It's actually the first glaze I've made that I've really liked, and I can now see why people get hooked on the whole voyage of discovery with glazes. Thank you once again so much for your generosity. I know I'm not the only one who appreciates it.

Peter said...

Hi PP,
Thank you for the lovey comment, I'm glad that you are enjoying the green/blue glaze. It would be great to see some photos, but I don't think it is possible to send such things via the comments section of the blog. You are most welcome to email me and send them that way. You should be able to track my email address down in the Contact page of this blog.

Do let me know how you get on with the matte glaze and with any colours you try, it will be very interesting and helpful to see how it works on other clay bodies and with glaze materials from different parts of the world.

Best Wishes,


Unknown said...

Happy New year Pete. Thanks for all your support with my glazing. I’ll try the mat glaze. I do aboriginal design and excited to experiment.

Peter said...

Hi "Unknown",
Lovely to hear from you. Do try the matt glaze, it has been working very well for me. I am interested that you do aboriginal design, and would love to see what you do. You are welcome to Email me with a photo of your work sometime. My contact details are on the Contact page of this blog.
Happy New Year to you!


PP said...

Hello Peter

Thought I'd report back on some test tiles I did, using your matte glaze with ingredients in the UK. I made one as per your recipe above, and added some random orange stain to another, and copper oxide to a third (at least I think it was copper oxide - I'm in London and away from my tiles at the moment). What I got was a transparent, shiny glaze which pinholed! Quite possibly I did something wrong, since I'm such a glaze duffer. The copper addition went a rather dull green, and the orange stain was actually quite nice if you weren't looking for an opaque matte! (not sure whether your original is opaque or transparent and because of aforementioned glaze dufferishness, I can't tell from looking at the ingredients). I'll have another go soon.

Hope things are well with you and that you're getting into your studio. You must be sliding towards Autumn there, whereas here we have a carpet of white snowdrops, with daffodils, primroses and bluebells all starting to peer above ground.

Peter said...

Hello PP,
Thanks for the report back regarding the matte glaze. All rather mysterious that you got something shiny and transparent... I don't really see how that could happen if glaze ingredients were of correct variety and weight. I had a slight panic when I read your comment as I wondered if I had made a x10 typo with one of the ingredients, but they all are as should be.

I made a big error myself today when making up a glaze, in that I weighed out 10 times the amount of the first ingredient (spodumene in this case) and blearily wondered why I had so little left in the bag. Fortunately the penny dropped before I added the second ingredient, and I was able to sort things out with no damage done!

We had a really hot day here today, fortunately my studio is in the shady side of the building so was able to occupy it and feel very thankful for somewhere that wasn't boiling! The cats are not very impressed by extremes of weather, but Nigella Stopit makes use of a large shallow stoneware bowl that is out by our back door, and fits herself into it. I guess that it is reasonably cool!

We are at the "overblown" end of summer where the days are shortening, and the birds are full of plums! Autumn not in sight as yet.

Snowdrops, daffodils, primroses and bluebells do sound very nice indeed!

Best Wishes,


PP said...

Hello Peter.

I re-made the glaze, and curiously it turned out the same as before, ie pinholey, transparent and glossy! I do know I'm not the world's greatest glazer (to put it mildly), so it's quite possible I've stuffed up identically twice. Or possibly the different ingredients here affected the glaze so utterly that it bears no resemblance whatever to yours?! So I'm still on the hunt for a S/W matte that I can colour... (it's a useful diversion from the hand building I 'should' be doing but have hit a wall with).

I hope Autumn is progressing apace there and that you've got some relief from the heat. Here Spring bulbs are spurting out of the ground with what I fear might turn out to be ill-founded confidence since we haven't really had Winter proper yet.

All the best.

Peter said...

Hello PP,
How sad that the glaze isn't working for you for some reason. Interesting that the same thing happened twice in a row, so not likely to be a problem with weighing an ingredient. I did have lengthy correspondence a few months ago with someone who was trying one of my other glazes and, after many repeat tests, did finally discover that one of their glaze ingredients had been wrongly labeled (Reminds me of an old song that had a line in it "What he thought was H2O was H2SO4"!). I suppose that there is no chance that one of the white powders that you are using is something like Lithium carbonate instead of Whiting? Or a high Sodium frit, such as 4110 instead of Soda Feldspar? It really does seem from your description like the glaze has been contaminated by a powerful flux of some kind. Lithium carbonate or a Sodium frit would give a result like that.

We currently enjoying a small crop of home grown potatoes, and are looking forward to a crop of pumpkins in a few weeks. The potatoes were more entertaining than anything else as they flowered very prettily, but were rather lacking in motivation when it came to actually growing potatoes in any quantity!

Hope the Spring bulbs bloom cheerily!

Best Wishes,


peter johnson said...

Greetings from the land of large blowflys. Great to see those fish.. YOU ARE PAINTING AGAIN!!!
That took a while, mate. The North was full of Auckland TYPES, so I'm on Phillip island.. Which is full of melbournites, wallaby, and PENGUINS. Found the nice clay.. Again.. Box of fibre and glaze suff arrived last week, shelves full of bits, so no excuses! Gooseneck pottery.. Worth a look on the Web. I may be assisting in the winter firing by crikey. Proper pottery.. Oooo. Give the Mrs a squeeze from me.. And one for yourself as well. Cheers

Peter said...

Hello There Peter,
Wonderful to hear from you from that hot, dry land of the fly just over the horizon! I'll peer at Google Maps and locate Philip Island. Delighted that you are potting over there and helping Gooseneck pottery on a winter firing would be great fun. I'm not far off cranking up my wood fired kiln again after rather a long break. Lots of pots to glaze that are on my shelves in the studio, and it would be really nice to fire them "properly" for a change with real flames rather than glowing Elephants... or what ever those wiggly things in the kiln are called!!
Had some great help recently stacking firewood, so no excuses!
Laura sends greetings!
All the Best,
Peter & Laura && Feline assistants!

peter johnson said...

Yes.. Cuddles to cats!
Little glaze test firing yesterday.. The standard J D boos wonder..
All good..
No excuses.. Pots.. Seals. dry. Build kiln. Yes, fear not the flame. Wheee

peter johnson said...

Recently joined a group.. Maybe you need to be innit! NZ studio pottery.
Sarah Geary says hello. (I put up the munitions factory shot) I think she recognized the lovely pot belly etc in background.. Cheers

Peter said...

You're up and about bright and early! The JDB is amazing really for temperature range that it will work at, hope it went well. A shame that some enterprising potters couldn't have painted some onto the Space Shuttle ceramic tiles. Always an interesting thought as to the firing possibilities of a space craft on re-entry! Perfect reduction for a while with so little oxygen available!
Have fun!